High speed cruise swimmy

[garyS-NJ]

Took my first longish cruise today in south jersey where you can generally cruise pretty fast (& after superbike races and eager to see my gf, I was cruising fast-ish). Anyway, with good skins, good tire pressures 38f, 40r), & I think good front end and rear, I found the bike swimmy around 100mph. I've heard guys with sport bikes saying their bikes stick to the road faster they go, but my bike 100mph felt close to a death wobble. There's no clunk in the neck.. where should I look first.. oh and I already chopped my ws down about 6".(back pressure and buffeting sicker with that big ws).

[Yammer Dan]

Been there. Don't want any more of That!!! I cured mine when I changed tire, balanced as well as I could and adjusted head bearings while keeping a good eye on tire pressure. Mine started about 100 MPH in long sweeping turns. I didn't use brake just backed off til it stopped and then used rear brake. Then went home and changed shorts!!!

[cowpuc]

Ditto with DanL.. I would also take a good look at the fork springs (if they are sacked and ready for progessives this can cause it) and freshen up the fork fluid (had a CB1100F that I bought CHEAP cause the PO got into a tank slapper on it at 130 and thats how I cured the issue). Maybe even double check lateral movement in swingarm assembly.. Bottom line, that 1st gen should run/ride happily at 100 and above no problem..

[bongobobny]

Yah!! That's my guess too! May be a combination of things! Bad tire, unequal fork springs, neck bearings, wrong torque on neck bearings, etc. etc. etc. Now the question being, did you ever have the bike up to those speeds previously successfully, and now the problem has started, or is this the first time you have had the bike up to those speeds?

 

Another high speed handling accessory to have on the bike is a super brace heavy duty fork brace installed to stiffen up the forks. The stock fork brace is flimsy and prone to allowing a little bit of flex between the forks. The Super Brace is thicker and tends to keep the two forks more stable and acting as a single unit...

[garyS-NJ]

I think I've had the bike up to 110 before but not all that long. I don't remember feeling all that comfortable in terms of bike stability.. I've heard guys with big sport bikes saying their bike actually get more stabile at higher speeds as the fairings act to push the front end down. At high speeds my front end actually feels light as if she was taking off.. It was doing a snake like when you ride a dirtbike in sand and you have to let the front swim around.. regarding the fairing, I have my front lowers removed. Could that be a significant drawback at 100mph? I have not yet even checked the fork oil and IDK if she needs new front springs (30K miles?). But my front end feels good as I don't hear or feel any neck bearing clunk looseness (but I've read that the bearings need to be preloaded just so, and I imagine over tight bearings would not be good). with the front end lifted, the fork rotates easy enough and no noticeable play in the neck.. and with the front down and a handful of front brake, the front shocks seem to be dampening enough.. I just remembered perhaps significant, my CLASS works for the front (I forget where I set it) but doesn't work for the back (I get the E1 code). And even with just my weight (160lbs), if I hit a good bump, I can hear the back clunk like I'm bottoming out. Maybe my swing arm bushings are loose?? gotta check that too. just hard to believe I can ride fine at 80MPH with a loose swingarm though.

 

And my tires are almost new Shinko 777's mounted and balanced by the dealer.. (and he said my front wheel balanced fine with no weights)..

 

I know from experience that low pressure in the rear tire will make a bike swimmy/unstablie on the highway. could my front vs rear suspension air pressure have the same effect? Oh, and a big hell yea on the fork superbrace but they are a tad expensive and I think I should go through the other stuff first. good post here seems to point towards neck bearings: http://www.venturerider.org/forum/showthread.php?29566-Front-wheel-wobble

[bongobobny]

That's the usual culprit!! Unless you or someone else replaced, or at least repacked the bearings, by now considering the age, your bearing grease is probably more like glue...

[Flyinfool]

What Bob said.

and

The front springs will die of old age not miles, those springs may well be toast. @cowpuc does a good job of explaining how to check this.

[Yammer Dan]

I did the springs and brace later. Check your rear Swing Arm bearings to make sure they are not shot. All good answers here. Start with the easy. Tires, Pressure, Adjust head bearings, Pressure in Forks, Super Brace, Springs,

[cowpuc]

Another thought,, its not uncommon for the fork tube bushings under the fork seals to get worn out of spec.. Sometimes, but not always, this wear will show up in seals leaking fluid.. Lots of times those bushings are overlooked in the seal replacement process.. Wear in those bushings will result in the tubes being able to move in the fork leg enough to cause some pretty strange feeling steering charactoristics and could easily be what your dealing with..

[garyS-NJ]

Any links on checking fork spring health or those fork tube bushings??

[Rotten]

I know its an old thread but. Did you resolve your issue?

 

 

 

I have a 96 Royal with Shinko 777 HD tires and had wobble and weave going on. I replaced the stem bearings, the stock were slightly bad. I've checked everything. The final straw was when I rode route 21 and the bike wanted to go straight, then the back said f u Im hitting the outside of the turn.

 

My shinkos suck, the front was out of round egg shaped and the rear had a a low spot just off center tread to the side wall. These tires have less then 1000 miles. Off they go and into the trash, Dunlop E3 going on stock size all around.

[cowpuc]

I know its an old thread but. Did you resolve your issue?

 

 

 

I have a 96 Royal with Shinko 777 HD tires and had wobble and weave going on. I replaced the stem bearings, the stock were slightly bad. I've checked everything. The final straw was when I rode route 21 and the bike wanted to go straight, then the back said f u Im hitting the outside of the turn.

 

My shinkos suck, the front was out of round egg shaped and the rear had a a low spot just off center tread to the side wall. These tires have less then 1000 miles. Off they go and into the trash, Dunlop E3 going on stock size all around.

 

Ya know what Rot,, cha may be onto something here.. I just ordered my 3rd Shinko 230 for the season.. All went really really well with the first two = also 230's.. I was suggested that I try 777HD's to increase my mileage - I run heavy on hot tarmac - used to getting 5k max out of rear.. Was in the process of ordering the 777's when I noticed the non-typical tread pattern of those tires.. Not long ago I wore out a set of Avon Venoms that had a similar non typical tread pattern and they displayed some similar charachteristics as those you describe.. The looks of the tread pattern on the tire (and what they left on dirt) was kinda cool but they just did not have the proper feel to them IMHO.. As they wore, they got worse.. Talk about spooky on road snakes!!

I examined those tires very carefully upon removal and also noticed an odd wear pattern - little more wear where there was less distance between the tread cuts..

I decided to go back to the 230's instead of trying the 777's partially because of what I saw there.. Now that I have read what you wrote, I think I will wait even longer before trying the 777's in a long distance tour.. If I do get a chance to pick one up locally here for cheap cheap (under 50 bucks) I will test it and see if I get the same results as you..

Thanks for your reply to this old thread!!

Puc

[KIC]

I had a "swimmy" which is a good way of stating it. It started after I developed an issue with my CLASS system which allows my front forks to overfill when raising my rear shock pressure. One point it seemed to somehow blow fork oil out my rear CLASS inlet. I know this all sounds bizarre, but I found fluid draining from my CLASS.

 

The "Swimmy " started after that and I chased different repairs until I connected the two events and decided to check my fork oil level, I had replaced my fork oil correctly when I installed my new Progressives. I was shocked at how low my right tube was compared to my left tube. Both were low, the right was very low.

 

I added the correct amount in each one and the shimmy went away. I guess the "micro" difference in the tubes compression at speed allowed the front wheel to feel like it was on ice especially on a sweeping turn.

 

Anyway, that's my story and I'm sticking to it.

Edited August 24, 2017 by KIC

[Yammer Dan]

I found tire pressure to be the most guilty in this. But I kept the front at 42 lbs. Below that it would start acting up at high speed if I did accidently break the speed limit. A few don't agree with that but me and my 1st Gens went go down the road!!